London has been battered by 50mph winds that have felled trees and caused travel chaos. Powerful gusts swept across the capital as the Met Office issued a yellow "be aware" weather alert for most of the country.

Detectives probing the disappearance of Madeleine McCann revealed today they are hunting a sex fiend who assaulted five other young British girls on holiday on the Algarve.

In a sensational development, Scotland Yard announced officers are investigating 12 potentially linked crimes in holiday resorts near to where Madeleine vanished in 2007.

In every case a man broke into mainly holiday villas occupied by British families -—and in four of them he assaulted five young white girls aged seven to 10 as they lay in bed. On one occasion he assaulted two girls in the same villa.

Many of the attacks were between 2004 and 2006, which was the year before Madeleine went missing from her bed in a holiday apartment in Praia de Luz. The most recent break-in was reported in 2010.

Police say that while the crimes are not identical, most are similar. There were no signs of forced entry, nothing was taken and the intruder appeared between 2am and 5am.

Most of the offences took place in the low season and on two occasions people reported hearing the noise of a bin collection lorry nearby.

Detectives believe that the suspect may have been in a villa looking around "for some time" before committing the offences.

In some cases the parent or the child woke up and disturbed the intruder but police say the man stayed calm even when confronted.

This distinctive red hooped t-shirt is linked to the huntMadeleine McCann disappeared in Portugal in 2007
Of the 12 cases, two occurred in Praia de Luz — where Madeleine was staying when she disappeared — four in the holiday resort of Carvoeiro and six in the Vale da Parra and Praia da Gale districts west of Albufeira.

Detectives believe there could be more cases of similar crimes where victims' families did not bother to report them to police. They urged those people to come forward and released an image of a distinctive red T-shirt linked to the hunt.

Madeleine was three when she vanished from her holiday apartment as her parents Kate and Gerry dined at a nearby tapas restaurant with friends in May 2007.

A Portuguese police inquiry into the case closed in 2008 but Scotland Yard opened a new review of the evidence in 2011 after an intervention from David Cameron. Det Ch Insp Andy Redwood, leading the inquiry, today said police needed to establish the identity of the sex attacker.

He added: "These offences are very serious and no one has been charged in connection with them. We need to eliminate this man from our inquiries and establish if the offences are linked to Madeleine's disappearance.

"If anyone has been a victim of a similar crime, please come forward even if you reported it to police in Portugal or anywhere else.

"Please do not assume we've been made aware of it. While some of these offences have been in the public domain before, following our appeal in October, three more were reported to us as a direct result of that appeal." He added that one of those reports was the first in the possible linked series of crimes.

Detectives revealed that they have received more than 5,000 calls from the public after an appeal for information and the launch of a full criminal investigation last year.

They are still trying to establish the identity of a man who was seen by three witnesses carrying a child matching Madeleine's description and who was walking towards the beach or town at 10pm on the night she disappeared.

Detectives said in six cases the intruder sat on or got into bed with the young girls. He carried out a “grim” serious sex assualt on five victims.

Children as young as two were present when he entered some of the rooms of the holidaymakers.

Witnesses described the man as having dark, tanned skin with short, unkept hair. He spoke English with a foreign accent with slurred speech. Sometimes he was bare chested, but two witnesses said he wore a distinctive burgundy T shirt with a white cicle on the back.

Three of the incidents were reported to Portugese police at the time - but, crucially, details werenotpassed on to the British investigation, raising further doubts about the original police investigation.

Deputy Assistant Commissioner Martin Hewitt, who is overseeing the Operation Grange inquiry, admitted he was “frustrated” by the slow pace of the investigation which requires British officers to submit legal “letters of request” to the Portugese before actions can be taken.

In further developments, officers revealed they have 38 “persons of interest” or possible suspects, they have taken over 500 statements, generated 5,569 “actions“ and identified 530 sex offenders, 59 of whom are classified as high risk.

A spokesman for Gerry and Kate McCann said they were grateful to people for coming forward and for the “thoroughness” of the Met inquiry.